In language as understated as her paintings, Choi (Nim and the War Effort) describes the daily routine of New Cat, who lives in a Bronx tofu factory owned by her best friend, Mr. Kim. Among the pet's responsibilities are cleaning the computer monitor with her tail, tasting tofu (only when Mr. Kim puts it in her bowl) and keeping the factory clear of mice. One night New Cat chases a mouse that enters the forbidden production room and, though she fails to catch her prey, manages to halt the spread of a fire that breaks out. Taking liberty with traditional scale and proportion, Choi offers several images that will tickle youngsters. One illustration reveals the smug mouse in the foreground, taking refuge under a piece of furniture while a glowering New Cat peers into her hiding spot; another shows the soggy pet at close range, peeking out from the bucket of tofu that has protected her from the flames. But a predominantly dark palette of browns and grays weighs down the light, playful story line. Ages 5-8. (Mar.)